Objective: The aim of this systematic review was to examine the research evidence concerning the views and experiences of people with intellectual disabilities regarding their participation in and the effectiveness of relationship and sex education programmes. Methods: A systematic search of relevant electronic databases was conducted using defined inclusion criteria. All papers reviewed were from October 1998 to October 2018. PRISMA guidelines were followed in the design and reporting of the systematic review. Results: A total of eight studies published in English were included in the review. Data were analysed and the key themes identified were (1) designing and developing relationship and sex education programmes, (2) participating in relationship and sex education programmes and (3) perceived benefits of relationship and sex education programme participation. Conclusion: This review identified that people with intellectual disabilities are accessing relationship and sex education programmes and appear to find them helpful. Further research is required to investigate the extent to which programmes impact on long-term behaviours that enable the development of sustainable relationships and reduce the unintended consequences of sexual activities. Implications for policy, practice and future research developments are discussed.